This sound is like someone blowing into an empty old-fashioned coke bottle and it is coming from the front somewhere. It recently started just before I had the resonator pipe replaced and now it's pretty consistent. It's not quiet but it's not incredibly loud either. I don't think it has anything to do with the resonator pipe. Anyone know what this might be? Could just be more vibration but I'd like to know what vibrates so much it would cause the howling-like noise.